Anthracnose: A Disease Every Tree Owner Should Know About

Posted on: 26 February 2015

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While many tree diseases, such as Dutch elm disease and walnut blight, are species-specific, anthracnose is a disease that can affect many different types of trees and shrubs. If you have trees of any sort on your property, knowing a little about this common fungal infection can help you prevent, identify and treat it as needed.

What causes anthracnose?

Anthracnose is caused by four different species of fungi. Different species of anthracose fungi affect different variety of trees, but the symptoms are similar regardless of the species. Anthracnose fungi are spread from tree to tree through the breeze. The spores get caught in the air and blow into a tree's leaf, where they take up residence and begin to replicate.

How do you know if a tree has anthracnose?

The primary symptom of anthracnose is the appearance of spots on the leaves. These spots vary somewhat depending on the type of tree that's affected. They may be white, yellow, or brown in color, and often they are shaped like bulls-eyes, with dark centers and lighter outer rings. The spots appear in the spring, and as the season progresses, the tree often loses some leaves prematurely.

What should you think a tree has anthracnose?

If you suspect a tree has anthracnose, call a tree care professional to confirm the diagnosis. There are a number of more serious tree diseases, such as Dutch elm disease and thousand cankers disease, that may mimic anthracnose in their early stages, and these diseases usually require different treatment than anthracnose.

Once the diagnosis is confirmed, anthracnose is typically treated by pruning out the heavily infected branches. The tree may be sprayed with a fungicide to keep the infection at bay, and should be re-sprayed every spring for several years, especially if anthracnose is prevalent in your area. Raking up the leaves promptly after they fall from the tree will also help prevent re-infection the next spring, since the fungus over-winters in piles of leaves near the tree's base.

What are the consequences of untreated anthracnose?

Anthracnose does not generally kill trees. However, it does weaken trees and may leave them more prone to other more serious diseases, which may lead to death. Anthracnose may also make a tree less able to withstand challenges such as periods of drought or air pollution. Thus, it's best to treat anthracnose as soon as possible, or else you may end up with a dead tree a few years down the road.

Keep an eye on your trees, and if you start seeing spots on their leaves, call a tree care service like Pete & Ron's Tree Service promptly. Anthracnose is a common problem, and by treating it, you not only improve your own tree's health, but also help reduce its spread to other trees in the area.